1 files changed, 59 insertions, 0 deletions
diff --git a/deps/acorn-plugins/acorn-class-fields/index.js b/deps/acorn-plugins/acorn-class-fields/index.js
new file mode 100644
index 0000000000..20348c80c6
--- /dev/null
+++ b/deps/acorn-plugins/acorn-class-fields/index.js
@@ -0,0 +1,59 @@
+"use strict"
+
+const acorn = require('internal/deps/acorn/acorn/dist/acorn')
+const tt = acorn.tokTypes
+const privateClassElements = require('internal/deps/acorn-plugins/acorn-private-class-elements/index')
+
+function maybeParseFieldValue(field) {
+  if (this.eat(tt.eq)) {
+    const oldInFieldValue = this._inFieldValue
+    this._inFieldValue = true
+    field.value = this.parseExpression()
+    this._inFieldValue = oldInFieldValue
+  } else field.value = null
+}
+
+module.exports = function(Parser) {
+  Parser = privateClassElements(Parser)
+  return class extends Parser {
+    // Parse fields
+    parseClassElement(_constructorAllowsSuper) {
+      if (this.options.ecmaVersion >= 8 && (this.type == tt.name || this.type == this.privateNameToken || this.type == tt.bracketL || this.type == tt.string)) {
+        const branch = this._branch()
+        if (branch.type == tt.bracketL) {
+          let count = 0
+          do {
+            if (branch.eat(tt.bracketL)) ++count
+            else if (branch.eat(tt.bracketR)) --count
+            else branch.next()
+          } while (count > 0)
+        } else branch.next()
+        if (branch.type == tt.eq || branch.canInsertSemicolon() || branch.type == tt.semi) {
+          const node = this.startNode()
+          if (this.type == this.privateNameToken) {
+            this.parsePrivateClassElementName(node)
+          } else {
+            this.parsePropertyName(node)
+          }
+          if ((node.key.type === "Identifier" && node.key.name === "constructor") ||
+              (node.key.type === "Literal" && node.key.value === "constructor")) {
+            this.raise(node.key.start, "Classes may not have a field called constructor")
+          }
+          maybeParseFieldValue.call(this, node)
+          this.finishNode(node, "FieldDefinition")
+          this.semicolon()
+          return node
+        }
+      }
+
+      return super.parseClassElement.apply(this, arguments)
+    }
+
+    // Prohibit arguments in class field initializers
+    parseIdent(liberal, isBinding) {
+      const ident = super.parseIdent(liberal, isBinding)
+      if (this._inFieldValue && ident.name == "arguments") this.raise(ident.start, "A class field initializer may not contain arguments")
+      return ident
+    }
+  }
+}